Currently, the data traffic transported over the telecom optical transport networks is growing at a phenomenal pace and consequently the transmitted bit rates over a single optical wavelength in a DWDM transport systems are increasing rapidly. It is expected soon that the standardized 100 Gb/s bit rate will not meet the need and a higher digital rate is required.
Currently, transport equipment is designed with standardized interfaces and DWDM interfaces where multiple optical wavelengths are used to transport various digital bit rates. International Telecommunications Union (ITU-T) Recommendation G.709 defines the optical transport network (OTN) interfaces and hierarchy. G.709 also defines the largest container ODU4 to transport 100 Gbit/s of data traffic.
Standards for the transport of data traffic greater than 100 Gbit/s, for example 400 GBit/s or greater, are not yet defined.